从mysql表中选择id的最大值并将其保存为变量

Question

是否可以从表中提取最高ID（在本例中为9）并将其作为变量$ maximum返回，以后可以用作整数？

Answer 1

您可以使用MAX()功能。可以找到文档here

Answer 2

您可以尝试以下代码段：

$sql =  "SELECT * FROM some_table where id = (select max(id) from some_table)"; 
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "id = " . $row["id"];
    }
} 

Answer 3

尝试一下，它将必须工作。

$sql =  "SELECT id FROM some_table ORDER BY id DESC LIMIT 1"; 
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "id = " . $row["id"];
    }
} 

Answer 4

尝试一下，它将必须工作。

$sql =  "SELECT id FROM some_table ORDER BY id DESC LIMIT 1"; 
$result = $conn->query($sql);
$id = 0; 
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        $id = $row["id"];
    }
} 

echo $id;